Titanate and metal interconnects for solid oxide fuel cells

Abstract

A solid oxide fuel cell (SOFC) includes a plurality of sub-cells. Each sub-cell includes a first electrode in fluid communication with a source of oxygen gas, a second electrode in fluid communication with a source of a fuel gas, and a solid electrolyte between the first electrode and the second electrode. The SOFC further includes an interconnect between the sub-cells. In one embodiment, the SOFC has a first surface in contact with the first electrode of each sub-cell and a second surface that is in contact with the second electrode of each sub-cell; and the interconnect consists essentially of a doped M-titanate based perovskite, wherein M is an alkaline earth metal. In another embodiment, the interconnect includes a first layer in contact with the first electrode of each sub-cell, and a second layer in contact with the second electrode of each sub-cell. The first layer includes an electrically conductive material selected from the group consisting of an metal, a metal alloy and a mixture thereof. The second layer includes a doped M-titanate based perovskite, wherein M is an alkaline earth metal. A solid oxide fuel cell described above is formed by connecting each of the sub-cells with an interconnect described above.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)[0001]The present application is a continuation application of U.S. patent application Ser. No. 12 / 005,655, filed Dec. 27, 2007 entitled “TITANATE AND METAL INTERCONNECTS FOR SOLID OXIDE FUEL CELLS,” naming inventor Yeswanth Narendar, which claims priority from U.S. Provisional Application No. 60 / 877,503, filed Dec. 28, 2006, entitled “METAL INTERCONNECTS WITH TITANATE COATINGS FOR SOLID OXIDE FUEL CELLS,” naming inventor Yeswanth Narendar, and U.S. Provisional Application No. 60 / 877,504, filed Dec. 28, 2006, entitled “TITANATE INTERCONNECTS FOR SOLID OXIDE FUEL CELLS,” naming inventor Yeswanth Narendar, which applications are incorporated by reference herein in their entirety.BACKGROUND[0002]A fuel cell is a device that generates electricity by a chemical reaction. Among various fuel cells, solid oxide fuel cells use a hard, ceramic compound of metal (e.g., calcium or zirconium) oxide as an electrolyte. Typically, in the solid oxide fuel cel...

AI Technical Summary

Benefits of technology

The invention introduces doped M-titanates for use in solid oxide fuel cells (SOFCs). Specifically, n-doped M-titanates, such as n-doped SrTiO3 or CaTiO3, are less likely to form oxygen vacancies during operation, reducing lattice expansion issues associated with conventional p-doped LaCrO3. Moreover, these doped M-titanates act as an effective oxidation barrier to extend the operation life of SOFCs.

Problems solved by technology

Interconnects are one of the critical issues limiting commercialization of solid oxide fuel cells.

However, oxidation of metal interconnects during operation, thereby forming metal oxides, such as Cr2O3, and subsequent migration of metals of the metal oxides (e.g., chromium migration) to an electrode layer and / or electrode-electrolyte interface is one of the primary mechanisms leading to performance degradation in solid oxide fuel cells.

While metal interconnects are relatively easy to fabricate and process, they generally suffer from high power degradation rates (e.g. 10% / 1,000 h) partly due to formation of metal oxide, such as Cr2O3, at an interconnect-anode / cathode interface during operation.

However, doped LaCrO3 generally suffers from dimensional changes, such as warping or some other forms of distortion, and consequent seal failures in reducing conditions.

Another issue related to LaCrO3 is its relatively low sinterability.

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